correct backstack navigation

[el-veee]

Current behavior: Navigating using navcontroller buttons will cause user to need to retrace all steps they have taken. For example, user adds and removes counter 3 times and then lands on the home screen (1 counter). If they push the back button, they need to go back through the cycle of creating and removing counters before pressing Back closes the app.

Desired behavior: IF user is on two counter screen, Back navigation should take them back to One counter screen. IF user is on one counter screen, Back navigation should close the app (not retrace all user steps)